Essential Thrombocythemia - Principal Analysis in Children and Adolescents

Abstract

Essential thrombocythemia (ET) is a rare disease in childhood. In this disease, an increase in the number of platelets in the peripheral blood is observed due to atypical megakaryocytes in the bone marrow associated with proliferation. The clinical features of ET course and response to therapy are analyzed in childhood and adolescent patients. ET course was analyzed in 23 patients under 19 years of age. The diagnosis of ET was established on the basis of WHO criteria, which included evaluation of clinical data, laboratory tests (general clinical studies; morphological, genetic, histological studies of bone marrow), instrumental studies and assessment of response to treatment. The average age of manifestation of the disease was 9 years and 9 months, the average indicator was 9 years and 6 months. Organomegaly was detected in 13 (52%) patients, isolated splenomegaly in 7 (37.5%) and hepatosplenomegaly in 6 (37.5%). Bleeding occurred in 6 (19.4%) patients with a significant decrease in ristocetin cofactor activity. Von Willebrand factor (not more than 15%), thrombocytosis (2000 10 9/1). 10 (38.7%) patients had microcirculation disorders (headache, dizziness, indigestion), half of them had thrombocytosis 1000-2000 10 9/1. JAK 2 V6 17F mutation in 3 (9.7%) patients, CALR gene mutation in 7 (29.0%), MPL gene - 1 (3.2%) patient, remaining 13. In (58.1%) patients, habitual driver genes were identified. Translocation t (12:12) was found in 1 (3.2%) patient. Complete or partial response to single-component cytoreductive therapy in young patients was 70-80%. The rate of complete response during therapy with anagrelide and interferons is higher than with hydroxycarbamide therapy (42.9%, 47.4%, and 0%, respectively). Hydroxycarbamide is not used in first-line therapy in children.

 In the pediatric population of patients with ET, the "triple negative" group predominated. which made differential diagnosis with secondary thrombocytosis difficult. The risk of bleeding in children is higher than in the adult population, which is due to the large number of patients with severe thrombocytosis. With the development of hemorrhagic syndrome, microcirculation disturbances that do not respond to treatment, antiaggregant agents, we recommend that ANA therapy should be preferred over INF and IIU as the first-line cytoreductive therapy. According to the pharmacokinetic properties, not anagrelid, but interferon and hydroxycarbamide and anagrelid, the potential risk of development of myelofibrosis is high.